Heysen Tunnels

The Heysen Tunnels are twin tube road tunnels which carry the South Eastern Freeway under Eagle On The Hill in the Mount Lofty Ranges in South Australia.

Construction
The tunnels were excavated using a tunnelling machine normally used in heavy-duty mining operations which tunnelled through 500 m of rock for each tunnel at an average rate of 3 m per day. The tunnels were completed in 1998 and opened in March 2000.

Operation
Each tunnel carries three lanes of traffic. As at 2015, 45,700 vehicles passed through them daily. The maximum height of vehicles permitted in the tunnels is 5.3 m, the same as the Crafers and Mt Osmond interchanges. Laser height detectors monitor traffic to provide warnings to drivers before they attempt to enter the tunnel.

The tunnels are named after artist Sir Hans Heysen.